Aims: The aim of the present study was to verify the comorbidity of conduct disorder (CD) and behavioral/developmental disorders in children and adolescents, and to examine the traits of CD comorbid with them.
Methods: Subjects were 64 children (60 boys, four girls) who were resident at three institutions for delinquent children or who were conduct-disordered outpatients of a university hospital aged under 18 years. A diagnostic interview was carried out by experienced child psychiatrists and the intelligence score and the Adverse Childhood Experiences score were measured by a licensed psychologist.
Results: A total of 57 children were diagnosed as having CD, of whom 26 (45.6%) were diagnosed with comorbid attention-deficit-hyperactivity disorder (ADHD), 12 were diagnosed with comorbid pervasive developmental disorder (PDD, 21,1%), and 19 (33.3%) had no comorbidity of either disorder. Six children (18.8% of CD comorbid with ADHD) met the criteria for both ADHD and PDD. The group with comorbid PDD was significantly younger at onset (F = 6.51, P = 0.003) and included unsocialized type more frequently (chi(2) = 6.66, P = 0.036) compared with the other two groups.
Conclusions: Clinicians should be aware that not only ADHD but also PDD may be comorbid with CD. Establishment of the correct diagnosis is important because recognizing the presence of PDD will enable us to provide appropriate treatment and guidance, which may improve prognosis.